Abstract Background The synthesis of new ligand and transition metal complexes have drawn great attention in cancer treatment due to excellent DNA cleavage activities and high antitumor activity. Objective The purpose of this study was to synthesize a new Zn(II) complex with 2,2′-bipyridine (bpy) ligand, Zn(bpy) 2 (H 2 O)2(ClO 4 ), and to investigate the potential therapeutic activity against breast cancer. Materials and methods Zn(II) complex was obtained and structurally characterized using crystallography and other spectroscopic methods. The cytotoxic and apoptotic effects of Zn(II) complex on MCF7 breast cancer and HUVEC control cells were evaluated by WST-1, Annexin V and cell cycle analysis. Results The spectroscopic data demonstrated that Zn(II) complex was successfully synthesized. Furthermore, Zn(II) complex exhibited significant cytotoxic effect on MCF7 breast cancer and HUVEC cells (p < 0.01). MCF7 and HUVEC cells proliferation was reduced to 11.0% and 52.6%, respectively at 10 μM for 48 h. Additionally, Zn(II) complex significantly induced apoptotic cell death (84.87%) and caused S phase arrest (36.4%) in MCF7 cells at 10 μM (p < 0.01). Conclusions Zn(II) complex has great therapeutic potential for the treatment of breast cancer. However, further studies are warranted to identify the underlying mechanisms of apoptotic cell death and to reduce the toxicity of Zn(II) complex on control cells.